Small, electric handheld devices, such as a powered razor or a powered toothbrush, typically include a motor to drive another component, such as an eccentric weight. For example, a direct current (DC) electric motor is used to drive an eccentrically mounted component. Various design considerations, however, impact the performance of the motor and the construction of the electric handheld device. Current approaches to utilizing a motor in a small, electric handheld device may include DC motors and/or E-shaped magnetic yokes to be fit within a constrained space. For example, the handle of a powered wet shaving razor is commonly bulkier and/or larger than the corresponding manual wet shaving razor in order to accommodate the electronics, such as the motor. A bulkier and/or larger handle may result in a less than desirable ergonomic form. In one example, the smallest diameter of the handle of the Fusion®ProGlide™ Power wet shaving razor (available from The Gillette Company, Boston, Mass.) is about 11-12 mm. In this constrained space, a motor must be accommodated with sufficient output to drive the handheld device. Moreover, performance of the DC motors depends on vibration frequency which depends on the operating voltage. Although the vibration frequency of a DC motor can be changed, amplitude of the vibrations cannot be changed. Furthermore, vibrations of a DC motor are affected by attenuation (e.g., touching of the handheld device by a user), temperature, and/or aging. Generally, however, if a smaller space is desirable then a smaller motor is used, but performance of the motor and the driven component may be compromised or undesirable. Examples of a small, electric handheld device incorporating certain motors include U.S. Patent Application Publication Nos. 2010/0175207, 2008/0204177, 2007/0137043, and 2005/0046281 and U.S. Pat. Nos. 7,554,225, 7,015,602, and 6,933,630.
What is needed, then, is a linear motor to be accommodated within a handle of a small, electric handheld device in which the motor is smaller in width, has fewer parts, and is more durable compared to current approaches. The motor of the small, electric handheld device, though smaller in width, preferably performs (e.g., efficiency) about the same, if not better, than current handheld devices. Even more preferably, a frequency, such as a resonance frequency, of the motor assembly can be controlled more easily.